Continuous layboy



March 13, 1962 l. DALE ETAL 3,025,057

CONTINUOUS LAYBOY Filed June 20, 1960 7 SheetsSheet 1 m I w x l 233232:: I l I. I I

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CONTINUOUS LAYBOY Filed June 20, 1960 7 Sheets-Sheet 4 INVENTOR. lueunwDALE K [LE A.MEHD

' ATTORNEYS March 13, 1962 DALE ETAL CONTINUOUS LAYBOY 7 Sheets-Sheet sFiled June 20, 1960 HLE E INV HLD jLE A m flTTo ENE rs March 13, 1962 1.DALE ETAL 3,025,057

CONTINUOUS LAYBOY Filed June 20, 1960 7 Sheets-Sheet 6 .LJ l 1 ING VHLDg ZZ E G/LE A MEAD March 13, 1962 l. DALE ETAL 3,025,057

CONTINUOUS LAYBOY Filed June 20, 1960 7 Sheets-Sheet '7 INVENET 0R.

NGVHLD 04 flTTOR NE 75 3,625,057 Patented Mar. 13, 1962 Free Filed June20, 196i Ser. No. 37,423 Claims. (Cl. 271-68) This invention relates toimprovements in layboys as used by the paper making industry for thestacking of paper sheets as discharged from the paper cutting machines.

It is the principal object of this invention to provide a novel andpractical mechanism for continuously stacking sheets of paper, assuccessively delivered into a stacking bin from the cutting machine, inconjunction with means for transferring stacks of paper sheets ofpredetermined count from the base or lower portion of a continuouslyforming stack without interruption in the paper cutting or sheetstacking operations.

It is a further object of the present invention to provide an improvedmechanism of the kind above stated, embodying therein, in conjunctionwith sheet stacking bins and stacking tables on which the stacks areformed, novel means for effecting separation of lower and upper portionsof the forming stack preparatory to the removal of the base or lowerportion of predetermined count, and novel means for giving temporarysupport to the upper or continuously forming portion of the stack whilesaid lower portion is being removed by the table and until the table hasbeen returned to stack supporting position.

Another object of the invention is to effect temporary support of theupper portion of the forming stack while the lower portion is beingremoved, by a novel arrangement and use of certain devices including aseries of belts that are drawn into and from stack supporting positionwith the travel of the stacking table to and from discharge position toreceive thereon and support the forming portion of the stack while thatportion of predetermined count is being removed and to do this withoutany sliding or frictional movement between the belts and the supportedstack that might result in misalignment or disturbance of sheets in theforming stack.

Yet another object of the present invention resides in the specificdevices employed for effecting the separation of the formed stack orpredetermined count from the upper portion of the forming stack, and intheir relationship to and use in conjunction with the stacking bins andstacking tables of the machine.

Still further objects and advantages of the present invention reside inthe details of construction and combination of parts and in their modeof operation, as will hereinafter be fully described.

In accomplishing the above mentioned and other objects of the invention,we have provided the improved details of construction, the preferredforms of which are illustrated in the accompanying drawings, wherein:

FIG. 1 is a plan, or top view, of a layboy embodying the improvements ofthe present invention therein, in readiness to receive paper sheets froma paper cutting machine, for continuous stacking.

FIG. 2 is a vertical section taken lengthwise of the machine on line 2-2in FIG. 1; showing a stack being formed on a stacking table.

FIG. 3 is a fragmental side elevation of parts of the present machine,showing in larger scale, the forming of a stack therein.

FIG. 4 is a fragmental side elevation, illustrating the removal, by thetable, of the lower divisional portion of a forming stack from thestacking bin of the machine.

FIG. 5 is a fragmental elevation showing the stack of predeterminedcount after being moved by the table to the discharge or unloadingposition and showing the sheets of the continuously forming stack astemporarily supported in the stacking bin by the stack dividers and theseries of belts.

FIG. 6 is a side view illustrating the stacking table dur ing its returntravel to initial position for the support thereon of the continuouslyforming stack.

FIG. 7 is a vertical section, taken through the backstop Wall of thestacking bin, showing a stack dividing shoe and its actuating solenoidmounted on the forward face thereof.

FIG. 8 is a vertical, sectional detail, showing the level anddisposition of the stack dividing fingers at the rearward or receivingend of the sheet stacking bin.

FIG. 9 is an underside view of a stacking table.

FIG. 10 is a side view of the stacking table.

FIG. 11 is a sectional detail at the receiving end of the machineshowing the stack dividing fingers and shoes as associated with thestacking bin and table.

FIG. 12 is an enlarged, cross-sectional, detail showing the means ofconnecting one of the stack supporting belts under spring tension with atransverse frame member.

FIG. 13 is an enlarged cross-sectional detail, taken on line 13-13 inFIG. 2, showing the air cylinder support and actuating means for thecross-beam that carries the stack dividing shoes.

FIG. 14 is a schematic layout of the electrical system employed forcontrol of the various devices employed in the operation of the presentmachine.

In the following description, the forward end of the machine will bethat which is at the right hand end in FIG. 2, while the rearward endwill be that at the left hand end of FIG. 2. This same designationapplies to the stacking bin and parts associated therewith.

Referring more in detail to the drawings and particularly to FIGS. 1 to6 inclusive; it is to be understood that paper sheets, as designated bynumeral 10 in FIGS. 3 to 6, are successively and rapidly infed to thepresent stacking mechanism from a paper cutter, not herein shown butwhich would ordinarily be located adjacent the left' hand end of themachine, as seen in FIG. 2; the paper sheets 10 being delivered to thestacking bins on or between traveling belts of a conveyor systemdesignated generally in FIG. 2, by reference numeral 11.

On entering the machine, the sheets 10, as shown in FIG. 2, to passbetween paired feed rolls .12 and 13 and are delivered horizontallytherefrom into a stacking bin, B, against a back stop 14 and are droppedonto a stacking table, as at 15, to form a stack, such as thatdesignated at 16.

A sheet stacking mechanism of the present kind usually comprises asuccession of stacking bins, side by side, each equipped at forward andrearward ends with stack separating shoes and fingers. In the machine,as shown in FIG. 1, there are two stacking bins. However, since each binis like the other and has a table and similar equipment associatedtherewith, the following description of the one as shown in FIG. 2 willlikewise apply to all others that may be employed in the machine.

The stacking table on which the paper sheets are re ceived, as droppedinto the bin to form a stack, is caused to be gradually lowered, from apredetermined upper limit of adjustment, in accordance with the rate ofincrease in height of the stack thus to keep its top surface at the samelevel. After the stack, as formed on the gradually lowering table, hasreached a predetermined count, the stack dividers of this inventionlater described, are actuated into positions overlying and pressing downwardly against the forward and rearward top edge portions thereof. Thestacking table is then lowered sufiiciently to clear the top of thestack of predetermined count from the lower edge of the back stop of thestacking bin and the table is then advanced. The stack is thereby movedbelow and forwardly of the back stop, to a position for its lateralunloading or discharge for its conveyance from the machine.

Upon the removal of the stack of predetermined count from the stackingtable, the table is automatically raised to its upper level and isreturned to loading position for the support thereon of the continuouslyforming stack. With the full return of the table to stack supportingposition, the temporary stack dividing fingers and shoes are returned totheir original or retracted positions and stacking of infed sheetscontinues without interruption.

The stacking bin B, as seen in FIGS, 1 and 2, is bounded at its forwardend by the vertical back stop 14; at its opposite or rearward end by asubstantially vertical, pivotally suspended jogging wall plate 17 and atits opposite sides by stack separator plates or division walls 1818. Thestacking table, 15, onto which the sheets drop from the back stop toform the stack ordinarily constitutes the bottom of the stacking him, aswill be understood by reference to the showing of its position in FIGS.2 and 3. It is shown in FIGS. 1 and 2 that the stack separators orsidewalls 18-18 of the stacking bin are supported from and below atransverse frame member 20 with their lower edges substantially at thesame horizontal level of the lower edge of the back stop 14.

The back stop 14, as best shown in FIG. 7, comprises a vertical plate,disposed transversely of the machine. This is supported by a horizontaland transversely directed frame beam 24. It is shown in FIG. 1 that thebeam 24 is supported at its opposite ends by horizontal frame rails25-25, that extend lengthwise of the machine along opposite sidesthereof, for its adjustment vertically and also in a directionlengthwise of the machine to accomodate stacks of different height andlength.

Located adjacent what has herein been designated as the forward face ofthe back stop 14, as best shown in FIG. 7, are the stack separationshoes 26. These are suspended in laterally spaced relationship, atpredetermined intervals of spacing along the back stop from an angleiron cross-beam 28. This cross-beam 28 is supported at intervalstherealong by brackets 29, each of which is rigidly fixed to and extendsforwardly from a mounting plate 30. Each plate 30 is parallel to thebackstop and is slidably contained, at is opposite side edges, inchannel-like guideways 31 that are fixed vertically to the forward faceof the back stop. The crossbeam 28, and parts mounted thereby aresupported in operative positions relative to the backstop by an aircylinder 32 which, as shown in FIG. 7, is fixed vertically to thecross-beam 24 of the frame structure of the machine. A piston rod 32'extends downwardly from the air cylinder to support the beam and thecondition of the cylinder is normally such as to hold the cross-beam 28and shoes as mounted thereby in elevated position, as indicated by thefull line showing of these parts in FIG. 7. Upon fully exhausting airfrom the cylinder 32, the cross-beam 28 will drop to its lower level, asin dash lines in FIG. 7 for the purpose of engaging the toe ends of theshoes against the stack, as will presently be explained.

Each of the stack dividing shoes comprises a fiat, horizontally disposedplate that is beveled to a thin horizontal edge at its rearward or toeend. A longitudinal rib or flange 26f is formed centrally on the top ofeach shoe and each shoe is supported for limited forward and rearwardswinging movement by a forward pair 34 and a rearward pair 34' ofsuspending links, which pairs of links are fixed, respectively, at theirupper ends to horizontal shafts 3535 that are extended through androtatably mounted by the bracket l Associated with the links 34-34' ofeach of the swingingly suspended shoes 26 and fixed above the level ofbeam 28, to the vertically adjustable plate 30 is a solenoid 36. Thesolenoid 36 has a horizontal sliding core bar 36 with a pin and slotconnection 37 at its extended forward end with the upper end of a leverarm 37 that is fixed, at its lower end, to the cross-shaft 35.Energization of the solenoid 36 causes the core bar 36' to be retractedand to thereby effect the forward swinging of the lifted shoe from stackengaging position to retracted position, as shown in dash lines in FIG.7, at 26r.

The stack separating fingers 40, located at the rearward end of thestacking bins, as seen best in FIG. 8, are slidably mounted for endwiseretraction and extension beneath a plate 42 across which the papersheets 10 are delivered from the paper cutter into the bin B. Thesefingers are laterally spaced, in accordance with the spacing of theshoes at the other end of the bin, or as may be desired. At theirrearward ends, the fingers are fixed to a horizontal cross-bar 44 fortheir extension and retraction in unison; the bar 44 being extendedtransversely of the bin and adapted to be actuated forwardly andrearwardly by connections at its ends with the upper ends of rockerlevers 45, that are pivoted between their ends, on a cross-shaft 46 foractuation by a connecting rod 47 which, in turn, has operativeconnection, as has been shown in FIGS. 8 and 11, with the piston of ahorizontally fixed air cylinder 48. Normally the fingers 40 areretracted as seen in full lines in FIG. 8 and are moved into theirextended or functional positions simultaneously, with the dropping ofthe shoes 26 against the stack, as will presently be explained.

The table shown enlarged in FIG. 10, on which the paper sheets arestacked, as they are successively received in the stacking bin,comprises a horizontal top 50 supported at each of its opposite sides bya pair of crossed and pivotally joined levers 51 and 52; the pivotalconnection comprises a cross-shaft 53 that is common to both sets oflevers. It is further to be observed in FIG. 10, that the crossed leversof each pair are pivotally fastened, respectively, at their rearwardends, as at 53f, to the table top and to a base or carrier frame 54; thecarrier being equipped with wheels 55 mounted for rolling travel on ahorizontal trackway 56 formed with the base structure of the machineframe. At their forward ends, the levers have horizontal slidingconnections with the stacking table and carrier frame, respectively, asat 66 in FIGS. 3 to 6. This permits a scissors-like action of the leversfor the raising and lowering of the table top for the intended purposes.

Located between the top 50 and carrier frame 54 of the stacking table,is a fluid pressure medium cylinder 67 supported from the cross-beam 53that extends between the two sets of paired levers 51-52. A piston 67'with piston rod 671* extends rearwardly from the cylinder and is fixedat its end in a cross-head 6711 which mounts paired rollers 63 at itsopposite ends that are disposed between the diverging rearward ends ofthe crossed levers, as seen in FIG. 9, for rolling travel on camsurfaces of these levers. As the piston rod is extended and retracted,the action of the crossed levers causes lowering and raising of thetable top accordingly. Pressure medium for the cylinder is suppliedthereto under valve and pump control through pipe lines 69 and 63 thatare attached to its forward and rearward ends. This medium may bemetered by various means to the cylinder 67 under control of a sheetcounter, or the like, to cause table lowering at the required rate tomaintain the predetermined top level of the stack as it forms in thebin.

It. has been indicated in schematic view of FIG. 14 that a limit switchLS1 is actuated by a cam m or a rotary knife driving shaft S. Thisswitch gives an electrical impulse to a sheet counter C for each sheetdelivered into the bin.

It is further schematically indicated that a time delay relay 82 which,after a predetermined interval, actuates a control valve 67 for thecylinder 67 which causes the table to be lowered to down position forunloading travel. Further explanation will be given later in describingthe mode of operation.

Supplementing the shoes 26 and the fingers 40 as actuated to functionalposition, for the support of a forming stack while the formed stack ofpredetermined count is being moved to discharge position by the stackingtable, is a plurality of narrow belts 74 that have ends fixed to theframe structure, as at 71 in FIG. 8, to extend forwardly as shown inFIG. 1. Each belt extends horizontally, passing forwardly over a roller72 mounted between the upper ends of brackets 73 that are rigidly fixed,as well shown in FIGS. 3 to 6 to and extend upwardly from the rearwardend of the carriage or base structure 54 of the table. After passingforwardly and over roller 72 the belts are directed downwardly to alevel below the table trackway passing about a transverse roller 74 thatmoves with the table carriage then forwardly and are attached, eachunder spring tension, as best shown at 70' in FIG. 12 to a cross-beam 75that is fixed horizontally in the frame structure below the unloadingstation. Thus, as the table moves forwardly, the plurality of belts 70are drawn across the bottom of the sheet stacking bin, to support thesheets as delivered across the extended fingers against the back stop;this method of support of the forming stack during an unloadingoperation as illustrated in FIGS. 4, and 6. With return of the tablefrom unloading to stack receiving position, the rollers 72 and 74 passthe belts thereover without causing any relative movement of the formingstack and the supporting portions of the belts as extended between theroller 72 and their anchored ends. The springs 70 maintain stacksupporting tension on the belts at all times.

It is an important feature of this invention that the belt 70 issupported at the level of the top of the formed stack and just slightlybelow the level of the fingers 40. When the stacking table movesforwardly, in the removal of the formed portion of the stack the belts70 maintain their elevation and are drawn taut immediately below theforming stack as then supported on the extended fingers and shoes, aswill be understood by reference to FIG. 5. The forming stack is thussupported on the belts during the removal of the stack of predeterminedcount and until the stacking table is returned to initial position. In apresent operation, the belts 70 are spaced approximately three inchesapart. The feature of their use is that there is no relative movement atany time between contacting portions of belts and supported stack andtheir tension maintains the stack as supported thereon against sagging.

The stacking table, as mounted on its base or carriage structure, isreciprocally actuated, for the removal of the stacks of predeterminedcount from the bin to the stack unloading or discharge station and itsreturn to initial position, by means of an electric motor 75, referredto herein as the table motor which is mounted in the frame structure atits sheet receiving end as shown in FIG. 2. This motor operates througha belt connection 76, to drive a continuous chain belt 77 that isextended horizontally of the machine, beneath the table, passing aboutsupporting sprocket wheels 78 78'. A link 79 is pivotally connected atits ends as at 8080 to a link of the chain belt '77 and to the table.Thus, with the driving of the chain belt 77, the table will be caused tobe reciprocally moved upon the trackway 56, between stack receiving andstack discharge stations. Normally the motor 75 is inactive and thestacking table is located thereby at the stacking station, as seen inFIG. 2.

The top structure of the stacking table has incorporated therein theteaching of US. Patent No. 2,785,928, issued March 19, 1957 to Victor E.Hanson, in its top surface structure. This consists of the provision ofa multiplicity of air valves therein that are caused to be opened underthe weight of a stack resting thereon to permit the escape of air underpressure from an air storage chamber beneath the surface to theunderside of the bale to facilitate its sliding removal from thestacking table.

It is anticipated that the top surface structure of the table top ontowhich the stacks are unloaded shall likewise be equipped with valves andan underlying chamber for air under pressure. The means for controllingthe use of these air valves will be later disclosed.

The electrical wiring and the various controlled means shown inconnection therewith, in FIG. 14, will be described in connection withthe following explanation of the mode of operation of the machine. 1

Assuming that the present sheet stacking mechanism has been constructedas illustrated and described and that the stacking table has beenproperly positioned to receive and support sheets 18 as delivered fromthe paper cutter into the stacking bin, and that the stack dividingshoes 26 have been lifted to raised positions as in FIGS. 3 and 7 andthe fingers 40 retracted, its operation would be as follows:

Sheets of paper 10 are delivered in rapid succession by the infeed means11 against the lower edge portion of back stop 14 and drop therefrominto the stacking bin. As the stack builds up on the table top 50, thelatter is lowered accordingly, as required to maintain the top surfaceof the stack at a predetermined level; the downward movement of thetable being controlled by the sheet counter, as previously explained,which operates in conjunction with the rotary knife of the paper cutter.

After a predetermined number of sheets have been cut and delivered, thecounter actuates the control valve of air cylinder 48 which effectsextension of the stack dividing fingers 40 over the rearward top edgesurface of the forming stack and at the same time similarly causes theair cylinder 32 to drop the beam 28 and cause the extended rearward endsof the shoes 26 to drop against the top of the forward edge of thestack. This causes incoming sheets 10 dropped into the bin to then bereceived at their rear and forward edges upon the fingers and shoeswhich now function as stack dividers or separators as indicatedin FIG.4.

The counter also is electrically connected with and actuates the timedelay relay 82 which, after a pre-set time interval, actuates thehydraulic cylinder 67 to lower the table 15 to its down position as inFIG. 4 for forward advancement or movement of the stack thereon, beneaththe lower edge of back stop 14 to the unloading station in which it isshown in FIG. 5.

The down travel of the stacking table is. stopped by the engagement of astop 85 fixed thereto, with a limit switch LS2, which incident theretoenergizes the electric motor 75 to move the table forwardly and awayfrom the stacking position to the discharge station; the table travelbeing stopped by its contacting and actuating a limit switch LS3 whichis incorporated in the control system of motor 75. This limit switch LS3serves two additional purposes: First, it serves to start a blower motor86 to supply air to the table top 50 and also to energize the pushermotor 87 which is operable to actuate a pusher bar 88 to push the stackof predetermined count laterally from the table top onto a receivingtable 89.. The pusher bar 88 is shown at the top, right hand end ofFIGS. 2 and 3 and the receiving table 89 is indicated at the lower righthand end of FIG. 1. The pusher bar movement is stopped by its contactinga limit switch LS4 which causes the hydraulic cylinder 67 to raise thetable; its upward movement being stopped by a limit switch LS5 whichalso energized the table motor 75 to move the raised table back tostarting position, to be stopped by its contact with a limit switch LS6.

Limit switch LS6 also operates to stop the blower motor 86 and energizesthe solenoids 36 to retract the extended shoes 26 and start the pushermotor 87 to return the pusher bar to retracted position. When the shoes26 move into fully retracted position, they actuate a limit switch LS7which energizes the air cylinder 32 to raise the cross-beam 28 and theshoes mounted thereon above the stack level. As the shoes raise, theyactuate a limit switch LS8 which energizes solenoids 36 to extend theshoes, as in FIGS. 2 and 7, in readiness for dropping against the stackin the next stack dividing operation. Adjustment in positions of thevarious limit switches may be made to suit the work being done.

By the means above described, the continuous stacking of sheets ispossible and stacks of predetermined number of sheets or height may beremoved from a forming stack without interruption in the paper cutter ormeans for feeding of sheets to the stacking bins. The various parts ofthe machine may be easily and readily adjusted to accommodate sheets ofvarious dimensions.

What we claim as new is:

1. A continuous layboy mechanism for use in combination with a deliverymechanism for the continuous delivery and stacking of sheet material;said layboy mechanism comprising a stacking bin, a back stop memberagainst which the sheets engage in the formation of the stack, a movablestacking table normally positioned to serve as a bottom for saidstacking bin for the support thereon of the continuously forming stack,stack dividing means movable from normally non-functional position to aposition for effecting the dividing of a lower portion of a formingstack from the upper portion thereof, means for moving said dividingmeans to dividing position, means for moving said table from its normalposition for the conveyance of the lower divisional portion of the stackthereon to a discharge station, a temporary stack supporting means thatis caused to be progressively positioned, with the movement of saidtable toward the dis:- charge station, to serve as a temporary suppontfor the upper divisional portion of the forming stack while the stackingtable is out of its normal stack supporting position, said temporarystack supporting means including a stack supporting belt, means on saidstacking table for progressively supporting said belt in stacksupporting position in and across the area of normal position of saidstacking table incident to the movement of said stacking table to saiddischarge station, means for returning said stacking table to normalposition, means for causing said belt to be progressively removed fromstack supporting position with the return of the stacking table tonormal position, and means for causing the return of said stack dividingmeans to non-functional position with the return movement of thestacking table,

2. The combination recited in claim. 1 wherein said back stop is infixed position and said stack dividing means are located at the forwardand rearward ends of the stacking bin and wherein the stacking table iscaused to be lowered by means that is operated by and in accordance withthe delivery of sheets from the delivery mechanism.

3. The combination recited in claim 2 including means for causing anadditional lowering of thetable after division of the stack to clear thetop of the lower divisional portion thereof from th lower edge of saidbackstop preparatory to the movement of the lower divisional portion tothe discharge station.

4. The combination recited in claim 1 wherein said belt supporting meansincludes an upper roller mounted on the rearward end of said stackingtable and wherein said belt is secured at one end to and below saiddelivery mechanism, av lower roller secured to and below said stackingtable and below said upper roller, said belt extending over said upperroll and below said lower roller and the other end of said belt beingsecured below said stacking table.

5. In a continuous layboy mechanism of the character described; a sheetstacking bin having a transversely disposed vertical back stop fixedlysupported at its forward end, a sheet delivery mechanism, a movabletable normally positioned to serve as a bottom for said bin for thestacking of said sheets thereon, a plurality of fingers mounted beneathsaid delivery mechanism at the rearward end of the bin, a plurality ofsheet supporting shoes mounted by said back stop, means mounting saidshoes whereby said shoes are downwardly and rearwardly movable from aretracted position above the formed stack to an extended position oversaid stack and means for simultaneously dropping said shoes onto the topsurface of the formed stack whereby the shoes receive and sup port thenext incoming sheet, means for extending and retracting said fingersfrom a normally retracted position to an extended position across theadjacent top edge of a formed stack, means for moving the table toconvey the lower divisional portion of the stack to an unloading stationand for return of the table to normal position after unloading.

6. The combination recited in claim 5 wherein said stack supportingshoes are disposed at a level that is slightly above the lower edge ofthe back stop and said back stop is formed across its lower edge portionwith notches that receive the shoes therethrough in their rearward anddownward swinging action for stack division.

7. The combination recited in claim 1 wherein said stacking tableincludes an air chamber below the upper surface thereof and a pluralityof air release valves mounted in and projecting above the upper surfaceof said stacking table.

8. The combination as recited in claim 1 including means operating inaccordance with rate of delivery of sheets onto the forming stack foreffecting lowering of the stacking table in accordance with rate ofincrease in height of the stack, thus to maintain the top surface of thestack at a constant level above the lower edge of the back stop.

9. The combination recited in claim 5 including also, a sheet counterthat is actuated by and in accordance with delivery of paper sheets intothe bin for stacking and wherein the adjustment of said fingers and saidshoes from retracted to stack dividing positions is cont-rolled by saidcounter and their retraction is controlled in accordance with movementof the stacking table to normal position after unloading,

10. The combination recited in claim 9 including means for supportingsaid shoes for vertical adjustment on the back stop, an actuatingsolenoid for each shoe and means controlled by the sheet counting meansfor energizing the solenoids to simultaneously extend and retract saidshoes, and a movable support controlled by the stack counting means forsimultaneously lowering all shoes as extended, against the top of theforming stack.

References Cited in the file of this patent UNITED STATES PATENTS1,938,325 English et al Dec. 5, 1933 2,205,767 Lamb Jan. 25, 19402,228,887 Peterson Ian. 14, 1941 2,675,747 Greiner et al. Apr. 20, 1954

